Internal combustion (IC) engines are widely used to provide mechanical power in mobile and stationary applications. It is common for engines to use turbochargers to harness residual energy from the engine exhaust gases with a turbine driving a compressor to boost airflow to the engine. It is also known to use a power-turbine to harness additional mechanical power, or to drive an electrical generator. The later configuration is known as a turbogenerator.
Exhaust emissions from IC engines are increasing regulated by law. In particular, most developed countries regulate emission levels of both Oxides of Nitrogen (NOx) and particulates of unburned hydrocarbons. To control NOx emissions, it is common to recirculate a portion of exhaust gas (EGR) with intake air for combustion in order to reduce combustion temperatures, thereby inhibiting NOx formation. In the future, even lower NOx emissions will be mandated. Increasingly higher EGR rates are one option achieving even lower NOx emission levels, but historically, EGR systems become more complex, more difficult to control, and less efficient with increasing EGR rates. This situation is further amplified when employing typical EGR systems with turbogenerator-equipped IC engines.
Accordingly, a more efficient and controllable EGR system for high EGR rates for use with turbogenerator-equipped IC engines is needed in the art.